Device for mixing and measuring a quantity of liquid

ABSTRACT

A mixer comprising a platform (12) which is configured to be able to support a receptacle containing a quantity of liquid. The platform (12) being supported from a base (18) to be pivotable about a first axis and a second axis where the first and second axes are perpendicular to each other, a drive motor (37, 39, 40 and 42) provided between the base (18) and the platform (12) to cause joint pivotable movement of the platform (12) about both the first and second axes to effect a rocking action of the platform (12). A particular application of the invention relates to a device which can be used during blood collection to facilitate both mixing and quantity measurement of the blood being collected.

FIELD OF THE INVENTION

This invention relates to a device which can be used to effect mixing ofliquids.

SUMMARY OF THE INVENTION

A particular application of the invention relates to a device which canbe utilised during blood collection to facilitate the mixing of theblood being collected with an anticoagulant in such a way that the bloodcomponents to not become segregated. It should be appreciated however,that the invention need not be limited in its scope to such anapplication.

Accordingly, the invention resides in a mixing means comprising acentral support, a transverse member extending to each side of thecentral support, a platform supported from the transverse member to bepivotable about a substantially horizontal first pivot axis and about asecond pivot axis which is transverse to the first pivot axis, a drivemotor supported from the transverse member having an upright drive shaftwhich is coupled to the platform whereby rotation of the drive shaftcauses joint pivotal movement of the platform about the first and secondpivot axes and whereby the spacing between the drive shaft and platformis not affected by the loading on the platform, wherein the loading onthe central support by the transverse member is substantially balanced,a portion of the transverse member to each side of the centeral portionbeing resiliently deflectable in proportion to the weight of thecontents of the platform, a measuring means provided to measure thedegree of deflection of the portions to provide an indication of theweight and/or volume of the contents of the platform.

According to a preferred feature of the invention said platform isconfigured to receive a receptacle in the form of a closed bag formed ofa flexible material. Preferably the platform is formed as a tray havingupstanding sides.

The invention will be more fully understood in the light of thefollowing description of one specific embodiment. The description ismade with reference to the accompanying drawings of which:

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING

FIG. 1 is an isometric view of a blood collection monitoring apparatusaccording to the embodiment;

FIG. 2 is a sectional side elevation of the base portion of theembodiment;

FIG. 3 is a sectional end elevation of the base according to theembodiment; and

FIG. 4 is an isometric view of the tray support of the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The embodiment is directed towards a device which can be used for thecollection of blood and monitoring such collection.

According to a further preferred feature of invention the drive meanscomprises a substantially vertical upright drive shaft having alaterally extending support element, said platform being provided with adownwardly depending member pivotally engagable with the support elementwhereby rotation of the drive shaft causes said joint pivotal movementof the platform.

According to the preferred feature of the invention the interconnectionbetween the support and the base incorporate a weight sensing andmeasuring means.

The embodiment comprises a housing 10 having a lower portion 11 whichaccommodates a support tray 12 and a drive means for causingreciprocation of the tray. The housing further comprises an upperportion 13 which extends upwardly from one side of the base 11 andaccommodates an appropriate control switch 14, a display 15, and flowline support 16. Both the lower and upper portion 11 and 13 accommodatethe control circuitry for the device.

The lower portion 11 is essentially cubic in configuration and isprovided with an open upper face 17. The support tray 12 is configuredsuch that it is received within the upper face 17 and is supported to beable to be caused to pivot about two substantially horizontalperpendicular axes in the open face 17. The tray 12 is formed with anupper face which is recessed in a manner such that it will support ablood collection bag and will prevent substantial movement of the bag onthe tray as a result of the cyclic tilting action of the tray.

The support tray 12 is supported within the base 11 from a supportstructure 18 (see FIG. 3) which has a base 19 defined by a lower plate20 which is adapted to be fixed to the bottom wall of the lower portion11 of the housing. The base has an upstanding pair of parallel webs 21and 22. The upper ends of the webs 21 and 22 support the central portionof a beam 23 which extends to each side of the space between the webs 21and 22 and which supports an upright 24 and 25 at each end. The uprights24 and 25 are further interconnected by a secondary beam 26 which liesparallel to the primary beam 23 and is spaced upwardly therefrom.

The upper end of each of the uprights 24 and 25 pivotally supports asupport frame 27 through pivots 28 and 29 where the pivot axis betweenthe pivots 28 and 29 is substantially horizontal.

The support frame 27 is of a generally cruciform configuration where theend of each arm is formed with an upwardly extending portion whichprovides two pairs of upwardly extending arms. The arms of each pair ofarms are opposite each other and the axes interconnecting the pairs ofarms are substantially perpendicular. One pair of upwardly extendingarms 30 and 31 are pivotally mounted to the uprights 24 and 25 throughthe pivots 28 and 29 respectively to be pivotally supported from thebase element 19 about the axis between the pivots 28 and 29. The otherpair of upwardly extending arms 32 and 33 are each formed with aV-shaped recess 34 which each pivotally receive a pivot pin or shaft 35provided on the underneath the tray 12 towards each end thereof suchthat the tray is pivotally supported between the second pair of upwardlyprojecting arms 32 and 33 for pivotable movement about the axis of theshaft 35.

The central portion of the support frame which accommodates the secondpair of upwardly extending arms 32 and 33 is formed with a slot shapedaperture 36 which as a width greater than the width of the webs 21 and22 and which enables the support frame 27 to pivot over the base aboutthe pivots 28 and 29.

The base 19 also supports a drive motor 67 which is supported from thesecondary beam 26 to depend downwardly therefrom but which is receivedwithin an opening 38 provided in the primary beam 23 such that it doesnot interfere with and is not supported in any way, by the primary beam23. The drive motor 67 is provided with an upwardly extending driveshaft 69 which has a wheel 60 mounted to its upper end. The wheel 60 isformed in its upper surface with a socket 61 at a position offset fromthe central axis of the wheel 60 and the shaft 69. If desired the wheelcan be replaced by a crank or like device.

The underneath of the tray 12 is provided with a downwardly dependingshaft 62 which is formed at its lower end with a ball-shaped element(not shown) which is pivotally received within the socket 61. The shaft62 is located centrally on the tray 12. On rotation of the wheel 60 as aresult of the activation of the drive motor 67 the free end of thedownwardly extending shaft 62 is caused to orbit around the central axisof the shaft and wheel and as a result the tray 12 is caused to pivotabout the central axis of the shaft 69 between the second pair ofupwardly extending arms 32 and 33 and the axis between the pivots 28 and29 provided between the uprights 24 and 25 on the base 19. This jointcyclic tilting of the tray 12 about a pair of substantiallyperpendicular axes provides an action which facilitates the rapid andconsistent mixing of blood and anticoagulant within a bag which issupported on the tray 12.

The operation of the drive motor through the control circuit is suchthat each time the drive motor stops the wheel the tray is at the sameposition. This is facilitated by the present of the magnet mounted tothe wheel 80 (not shown) which is associated with a Hall effect sensor(not shown) provided on the secondary beam 26 to enable the controlcircuit to always stop the drive motor 67 with the tray in the sameposition. In use a receptacle is placed on the tray such that the inletis lowermost. As a result blood entering the receptacle must flowthrough the anticoagulant accommodated within the receptacle when thetray is stationary.

The mounting and construction of the tray is such that it can be readilylifted out of engagement with the recesses 34 on the arms 32 and 33 ofthe support frame 27 and out of engagement with the wheel for the trayto be cleaned. When cleaned the tray is readily capable of beingre-engaged with the support 27 and the wheel.

It has been found that the repetitive tilting of the tray about twoaxes, as a result of the construction according to the embodiment,enables the blood, collected during a normal six minute donation period,to be rapidly mixed with the anticoagulant contained within thereceiving bag with little segregation of the constituents of the blood,such as accumulation of red blood cells which has been a commondifficulty with mechanisms used in the past.

In this regard high concentrations of the anticoagulant has toxiceffects on blood while lack of anticoagulant results in the bloodresults in the initial phases of blood coagulation. If the mixing of theblood with the anticoagulant is slow or not even distributed the bloodcan remain segregated from the anticoagulant for an extensive period oftime. This results in the blood in contact with the anticoagulant beingsubject to excessive concentrations of anticoagulant and the blood lyingin the bottom of the bag which is separated from the anticoagulantcommencing the initial coagulation stages.

The primary beam 23 of the base provides the primary support for thetray, its contents and the support frame 27 from the base 19. Theprimary beam 23 is supported symmetrically from the webs 21 and 22 andalso symmetrically supports the tray 12 and its contents. The beam isformed with a set of four symmetrically located transverse grooves 39and each groove is associated with a strain gauge 40. The strain gaugesare interconnected to an electrical circuit which is able to provide ameasure indicative of the weight of the tray and its contents. Inaddition the control circuitry is able to provide a displayrepresentative of the weight of the contents of the bag in the tray andthe rate of change of the weight of the contents of the tray. Theconfiguration and construction of the primary beam may take anydesirable form to facilitate the symmetrical support and use of fourstrain gauges to provide a measure representative of weight.

In operation the drive motor 67 is activated intermittently wherebyduring each rest period the weight as sensed by the strain gauges 40, ismeasured and the change in weight since the previous rest period isdetermined.

The support arrangement for the tray according to the embodiment asdescribed above comprises a means whereby the pivotal support for thetray and the drive for causing such pivotal movement of the tray iscarried from a common carriage which is in turn supported symmetricallyfrom the base element whereby the nature of the support provided for thecarriage enables the weight of the tray, the support carriage and thecontents of the tray can be accurately monitored, to ensure accuratemonitoring of the contents of the tray 12.

The upper portion 13 of the housing is provided with a flow line support16 which comprises a set of three upwardly fixed extending spigots 41and a fourth movable spigot 42. The fixed spigots 41 together form atriangular array of spigots. The movable spigot 42 is capable of movingtowards the central spigot 41a. In use a blood flow line is lacedbetween the movable spigot 42 and the three fixed spigots 41. Themovable spigot 42 is associated with a latch means which is activated bya solenoid or like device which on activation will cause the movablespigot 42 to move towards the fixed spigots 41 whereby the flow line isclamped to prevent flow of blood through that line.

The control of the flow line support means 16 is effected from thecontrol circuit accommodated within the upper portion 13 of the housingto control the flow of blood to the receptacle carried on the tray 12.

The control circuit incorporates a main control switch 50 to initiatethe operation of the device. In addition the control circuit is providedwith a micro processor which in association with the display 15 providesa set of instructions to the operator and which controls the flow linesupport in association with those instructions. The control circuit isfurther provided with appropriate toggle switches 14 and memorycircuitry which enable a value for a predetermined volume of blood whichis to be collected to be introduced into the memory of the controlcircuit such that on that volume having been collected the flow linesupport will be activated to prevent any further flow of blood to thereceptacle. On first use of the device the volume or weight of blood tobe collected is stored into the memory. This can be varied from time totime but the memory will retain the figure previously entered until itis subsequently changed.

The control circuit is also able to provide a display of the amount ofblood collected by indicated the weight of blood collected or the volumeof the blood collected. In providing such the circuit operates on themeasure derived from the weight sensing circuit to provide a measure ofthe volume. If desired a suitable switch may be provided with thedisplay to be able to change the display from indicating weight toindicate volume during operation of the device.

The display provides a multiple of displays. On form of display providesan accurate digital display of the volume and/or weight of blood in thecollection bag and the time elapsed since the collection of bloodcommenced. The other form of display comprises an array of lights whichare activated sequentially whereby at the commencement of collection nolights are activated and at the termination of collection when thepredetermined volume of blood has been collected (irrespective of thatamount) all of the lights are lit. As a result the array of lightsenable a ready determination to be made of the percentage of the amountto be collected which has actually been received in the collection bag.The display can also provide a periodic audio signal indicative of thepercentage of the collection that has been received. This may comprise avariable signal which varies in pitch and frequency throughout thecollection period.

At the commencement of the use of the apparatus it is switched on andthe user is instructed by the display to locate a collection bag on thetray. Only after a collection bag is located on the tray 12 will beapparatus proceed to the next step at which the display is set toindicate zero in relation to both the weight and/or volume of blood inthe collection bag. The sensing of the presence of a collection bag inthe tray may be effected by sensing the increased weight of the tray dueto the collection bag or by means of a light sensitive cell located onthe tray. The flow line to the tray is then installed in the flow linesupport 16 and is connected to a donor. When the receptacle and flowline are in position, blood begins to flow to the receptacle and on aninitial quantity of blood being received (e.g. 20 grams) the controlcircuit activates the drive motor 67 to cause the cyclic tilting of thetray 12 about its pivot axes. Such activation of the motor isintermittent and is for a period of several rotations of the wheel.During each rest phase the weight of the tray and the receptacle ismeasured. The control circuit then compares the weight currently beingmeasured with the weight previously measured and provides an indicationat the display of the current weight of the contents of the tray.

If desired the display can also provide an indication of the flow ratewhich is derived from the change in weight of the contents of the traybetween the current measurement and the previous measurement. In theevent of the flow rate not being within a satisfactory range a furtherdisplay is provided and the display is associated with a suitableaudible alarm to draw the attention of the operator to the low flow ratein order that the matter can be rectified. After intervention by theoperator the operator may press the main control switch 50 again whereonthe control circuit will enable the display to continue as if theinterruption had not occurred.

In addition, the control circuit is such that it will not accept anyspurious indicators of mass or volume of the contents of the receptaclewhich is contrary to the expected flow rate from a donor. Such acircumstance can arise when an operator taps or touches the receptaclewhich results in an excessive weight being measured by the controlcircuit and where the weight measured is not representative of theactual weight of the contents of the tray. This rapid weight increasewould be beyond that which one would normally expect from a blood donor.The microprocessor is programmed not to accept any measurements whichare beyond the normal flow rates expected of a donor and which are notrepresentative of the actual flow rate to the bag. Therefore the controlcircuit ignores any spurious weight indicators that may result from thereceptacle being inadvertently knocked or tapped, and will not shut offthe blood flow in the event of such an incident.

The upper portion of the housing is also provided with a set ofphotovoltaic cells 51 which are associated with a set of electrolyticstorage batteries and a charging circuit. These enable the device to beportable and capable of being independent of a mains power supply.

The control circuit also includes a Calibration programme whereby theweighing sensor may be calibrated. The programme provides a sequence ofinstructions on the display. The instructions require the operator tolocate a set of standard weights (e.g. 10 g, 20 g, 30 g weightssequentially) on the tray and on location of each weight the circuitcalibrates the sensor. This Calibration programme can be initiated atany time the device is not in collection mode.

It should be appreciated that the scope of the present invention neednot be limited to the particular scope of the embodiment describedabove.

I claim:
 1. A mixer, comprising: a support element, a first transversebeam extending laterally from opposite sides of the support element, afirst pair of pivots provided on the first transverse beam, on oppositesides of the support element and equidistant from the support element,to provide a first pivot axis, a support pivotally supported from thefirst pivots to be pivotable about the first pivot axis, the supporthaving a pair of second pivots on opposite sides of the first pivot axisto provide a second pivot axis which is perpendicular to the first pivotaxis and which is located between the first pivots, a platform pivotallysupported from the second pivots to be pivotable about the second pivotaxis, a drive motor supported from the first transverse beam, said drivemotor having a drive shaft which is coupled to the platform, wherebyrotation of the drive shaft causes joint pivotable movement of theplatform about the second pivot axis and the support about the firstpivot axis, said first transverse beam being deflectable proportionallyto the weight of an item on the platform, and measuring means, connectedto the first transverse beam, for measuring the degree of deflection ofthe beam to provide an indication of the weight and/or volume of theitem on the platform.
 2. The mixer of claim 1, wherein the weightcarried by the first pivots is substantially equal.
 3. The mixer ofclaim 2, wherein the drive shaft and the platform are coupled by alaterally extending member provided on the drive shaft and by adownwardly depending member provided on the platform and pivotallyengaged with the laterally extending member, whereby rotation of thedrive shaft causes said joint pivotable movement of the platform.
 4. Themixer of claim 2, wherein the platform is configured to receive areceptacle in the form of a closed bag formed of a flexible material. 5.The mixer of claim 1, wherein the drive shaft and the platform arecoupled by a laterally extending member provided on the drive shaft andby a downwardly depending member provided on the platform and pivotallyengaged with the laterally extending member, whereby rotation of thedrive shaft causes said joint pivotable movement of the platform.
 6. Themixer of claim 1, wherein the platform is configured to receive areceptacle in the form of a closed bag formed of a flexible material. 7.The mixer of claim 6, wherein the platform is formed as a tray havingupstanding sides.
 8. The mixer of claim 1, wherein the platform isadapted to accommodate a blood collection receptacle.
 9. The mixer ofclaim 1, wherein the second pivots are spaced equidistant to each sideof the first pivot axis.
 10. The mixer of claim 9, wherein the weightcarried by the second pivots is substantially equal.
 11. The mixer ofclaim 9, wherein each of said first pivots is provided by an armextending from the first transverse beam, and said drive motor issupported from a second transverse beam extending between the arms. 12.The mixer of claim 9, wherein the platform is engaged with the secondpivots and the drive motor in a manner that allows the platform to bereadily disengaged the second pivots and the drive motor by lifting theplatform from the second pivots.
 13. The mixer of claim 1, wherein eachof said first pivots is provided by an arm extending from the firsttransverse beam, and said drive motor is supported from a secondtransverse beam extending between the arms.
 14. The mixer of claim 13,wherein the first transverse beam is provided with at least one straingauge to provide said measuring means.
 15. The mixer of claim 14,wherein the drive shaft and the platform are coupled by a laterallyextending member provided on the drive shaft and by a downwardlydepending member provided on the platform and pivotally engaged with thelaterally extending member, whereby rotation of the drive shaft causessaid joint pivotable movement of the platform.
 16. The mixer of claim13, wherein the platform is engaged with the second pivots and the drivemotor in a manner that allows the platform to be readily disengaged thesecond pivots and the drive motor by lifting the platform from thesecond pivots.
 17. The mixer of claim 13, wherein the platform isconfigured to receive a receptacle in the form of a closed bag formed ofa flexible material.
 18. The mixer of claim 1, wherein the platform isengaged with the second pivots and the drive motor in a manner thatallows the platform to be readily disengaged the second pivots and thedrive motor by lifting the platform from the second pivots.
 19. Themixer of claim 18, wherein the drive shaft and the platform are coupledby a laterally extending member provided on the drive shaft and by adownwardly depending member provided on the platform and pivotallyengaged with the laterally extending member, whereby rotation of thedrive shaft causes said joint pivotable movement of the platform.
 20. Amixer, comprising:a base; a generally vertical support mounted on thebase; a generally horizontal beam mounted on the support; a framepivotally mounted relative to opposite ends of the beam, wherein theframe pivots about a first pivot axis relative to the beam; a platformpivotally mounted relative to opposite ends of the frame, wherein theplatform is sized and configured to support an item, and the platformpivots about a second pivot axis relative to the frame, and the secondpivot axis extends generally perpendicular to the first pivot axis; adrive motor mounted to at least one of the base, the support, and thebeam; a generally vertical drive shaft interconnected between the drivemotor and the platform, wherein rotation of the drive shaft causes jointpivotable movement of the platform about the second pivot axis and theframe about the first pivot axis; and a measuring means, connected tothe beam, for measuring at least one of the weight and the volume of anitem on the platform.
 21. The mixer of claim 20, wherein the secondpivot axis is disposed equidistant between the opposite ends of thebeam.
 22. The mixer of claim 20, wherein the first pivot axis isdisposed equidistant between the opposite ends of the frame.
 23. Themixer of claim 20, wherein the measuring means includes a plurality ofgenerally transverse grooves formed in the beam, and a strain gaugeassociated with each of the plurality of grooves and connected to thebeam.